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<head>
  <meta charset="UTF-8">
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  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    let age = [15, 19, 21, 33, 18, 24]
    let sum = 0
    for(let i =0 ;i<age.length;i++){
      sum += age[i]
    }
    document.write(`同学们的平均年龄为${sum / age.length}`);
  </script>
  
</body>
</html>